CZ299869B6 - Transparent substrate and use thereof - Google Patents

Abstract

In the present invention, there is disclosed a transparent substrate for glazing of a glass substrate type being coated with a system of coatings comprising at least one functional layer with sun light protection capability, low emission capability and/or electric conductance and the final layer thereof being based on silicon nitride, carbonitride, oxynitride or oxycarbonitride wherein the layer based on silicon nitride, carbonitride, oxynitride or oxycarbonitride is covered by a protection layer being at the most 10 nm thick and deposited in the form of a metal being selected from the group consisting of at least one of the following metals: Nb, Sn, Ta, Ti a Zr, or deposited in the form of a metal oxide, being possible for these oxides to be substoichiometric in terms of oxygen, and being selected from the group consisting of one of the following oxides: niobium oxide, tin oxide, tantalum oxide, and zirconium oxide. Further disclosed is the use if the above-described substrate that c an be bent/hardened, as a glazing in buildings or automobiles.

Description

Transparent substrate and its use

Technical field

The invention relates to transparent substrates, in particular glass substrates which are provided with at least one layer having sun protection, low emissivity and / or electrical conductivity, and the use of these transparent substrates for the production of windows.

BACKGROUND OF THE INVENTION

The main application of the invention is the production of so-called functional windows used in construction or vehicle construction. In view of the above, the term "functional" window is to be understood to mean a window in which at least one of the substrates is coated with thin layers intended to impart to it special properties, in particular thermal, electrical, optical or even mechanical properties, such as durability anti-scratch.

The most interesting thin films according to the invention are those which provide certain thermal properties, i.e., those properties which are manifested in particular by reflecting long-wavelength infrared radiation and / or solar radiation.

Low-emissivity layers are known from the prior art, in particular a thin layer of silver or a layer with doped metal oxide, type F: SnO ₂ or ITO, filter layers, whose functional property is protection against the effects of solar radiation, for example nickel and chromium alloys, thicker silver layers, or TiN metal nitride layers.

The assemblies may comprise one or more layers, hereinafter referred to as "functional" layers. These layers are usually combined with other layers for various reasons to form an assembly (or combination) of these layers.

Thus, it is generally sought to combine these layers with at least one coating of dielectric material, and the coating (s) are deposited above the functional layer and / or sandwiched between the carrier substrate and the functional layer. This arrangement is recommended mainly for optical reasons:

these coatings, selected to have a suitable refractive index and a suitable thickness, allow the visual appearance of the window, in particular in reflection, to be modified in an interference manner. In addition, these layers deposited above the functional layer may also provide protection against chemical or mechanical damage. In this sense can be cited patents · EP 544 577, EP 573 325 and EP648 196, which describes a functional layer containing the F: SnO2 kombino40 blows sjinou type a dielectric layer of SiO _2, SiOC or SiON; furthermore patents EP 638 528, EP 745 569 and EP 678 484 disclosing assemblies using one or more layers of metal oxide dielectric, and EP 630 938 using a TiN-based layer combined with two oxide layers, or EP 511 901, according to which a layer of nitrided nickel and chromium type is used between two certain metal oxides.

According to recent research in this field, a solution has been found to use said layers of dielectric material to protect functional layers during high temperature heat treatment of their glass substrates such as bending or curing. Silicon nitride based materials have proven to be very useful, in particular for the following reason: optically having a refractive index close to 2, and thus this refractive index is similar to the refractive index of most of the metal oxides commonly used as dielectric layers, such as SnO ₂ . However, these materials also act as an atmospheric oxygen barrier to the functional layer, so that it protects it from oxidative disturbance at high temperature. Moreover, at high temperatures they are "inert" to oxygen in the sense that their properties, in particular the optical properties, remain unchanged after the bending and curing heat treatment. Thus, it is possible to create assemblies in which it is functional

The layer is coated with a Si3N4 layer, optionally combined with other layers, which remain the same after bending and hardening, as is known, for example, in EP 0 718 250, in which glass / oxide or oxide / silver / metal / layer assemblies are described. the oxide / Si ₃ N ₄ layer (s), the outer layer being formed of S 13 N 4.

However, it turned out that even in this type of assembly, the industrial yields were not optimal in the sense that a significant number of such coated substrates had to be discarded after bending or curing because of small hole optical defects that were apparent to the naked eye.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to overcome this drawback, in particular by providing a new type of assembly comprising a functional layer or layers that can undergo heat treatment while at the same time showing better optical quality or at least optical quality that is more reproducible and more controllable.

The invention relates to a transparent substrate for glazing of the glass substrate type which is coated with a coating system comprising at least one functional layer having sun protection, low emissivity and / or electrical conductivity and whose final layer is based on nitride, carbonitride, oxinitride, or a silicon oxycarbonitride, said nitride, carbonitride, oxinitride, or silicon oxycarbonitride layer being coated with a protective layer of maximum 10 nm thickness, deposited in the form of a metal selected from at least one of the following: Nb , Sn, Ta; Ti and Zr, or deposited in the form of a metal oxide, optionally with respect to the substoichiometric oxygen content, selected from at least one of the following oxides: niobium oxide, tin oxide, tantalum oxide, titanium oxide and zirconium oxide.

In a preferred embodiment of the transparent substrate, a layer based on nitride, carbonitride, oxinitride, or silicon oxycarbonitride is doped by introducing into its composition at least one typu type metal in a proportion ranging from 3 to 25% by weight.

According to a further preferred embodiment of the present invention, the protective layer is deposited in the form of a metal or in the form of a metal oxide which is substoichiometric in terms of oxygen content and oxidizes completely during the bending and / or curing heat treatment. It is also preferred according to this embodiment that the protective layer deposited in the form of a metal or in the form of a metal oxide which is substoichiometric in terms of oxygen content has a thickness in the range of 1 to 5 nm.

In another preferred embodiment of the present invention, the metal oxide deposited protective layer has a thickness in the range of 2 to 10 nm.

In another preferred embodiment, the functional layer is of the metal type, in particular based on silver, gold, aluminum, nickel, chromium or stainless steel,

In another preferred embodiment, the functional layer is a metal nitride type such as TiN, CrN, NbN, or ZrN.

In another preferred embodiment, the functional layer is a doped metal oxide type such as ITO, F: SnO ₂ , In: ZnO, F: ZnO, Al.ZnO or Sn: ZnO.

According to another preferred embodiment, the substrate is provided with a thin film stack comprising at least one silver-based layer disposed on one side between an "inner" dielectric coating and, on the other hand, an "outer" dielectric coating, preferably a silver-based layer. on a thin metal layer disposed on an "inner" dielectric coating, said outer dielectric coating comprising a silicon nitride-based layer.

-2GB 299869 B6

According to another preferred embodiment of the present invention the thin film assembly comprises at least two functional layers, in particular two or three silver-based layers.

In a further preferred embodiment of the present invention the thin film assembly comprises at least two functional silver-based layers and a final silicon nitride-based layer.

The transparent substrate of the present invention is preferably bendable / curable.

The present invention also encompasses the use of any of the above specified substrates for the manufacture of glazings having electrical properties such as heated glazing and / or having thermal properties such as sun protection, glazing with filtering capability or low emission capability that are bendable / curable.

Preferred is the use of the substrate of the present invention for the manufacture of monolithic or laminated glazing, especially glazing intended for use in buildings or cars such as windshields or side windows.

Accordingly, the present invention provides a transparent substrate, of the glass substrate type, coated with a thin layer based on silicon nitride, silicon carbonitride, silicon oxinitride and / or silicon oxycarbonide (hereinafter referred to as a "silicon nitride layer") or an array of thin layers of which the last layer is silicon nitride. Therefore, in order to prevent breakage of this layer during bending and curing heat treatment, particularly in contact with an atmosphere containing corrosive substances of the Na ₂ O type and possibly chlorides or sims, the assembly is therefore covered with a layer that protects against this kind of high temperature corrosion and / or doped by introducing at least one metal ion into its composition. (In this description, the term "doping" does not mean a term known from electronics, but rather indicates that the nitride layer exhibits properties, in particular it is high temperature corrosion resistance, which is enhanced by the presence of the metal additive (s). )

In fact, it has been found that the silicon nitride layer fully fulfills its role of protecting the bottom layers from high temperature oxidation. On the other hand, under certain conditions occurring in a heat treatment such as curing, in particular bending, this layer of silicon nitride may be susceptible to failure, not by oxidation but rather by reaction with chemicals present in the atmosphere in which bending takes place which is "aggressive" at high temperature and / or "migrates" from the second glass substrate when the bending of several of these glass substrates is carried out simultaneously, the substrates being stacked in a circular form and a multilayered assembly of one of of the substrates is in contact with the second glass substrate. In this context, at least one species has been identified: these are all alkali metal compounds of the sodium type, in particular Na ₂ O vapor. This high temperature sensitivity has so far led to the formation of the holes mentioned above where silicon nitride surface attack has spread to the rest. report.

The solution according to the invention therefore consists in preserving silicon nitride for its very useful oxygen barrier properties and improving its high temperature durability in two combined or alternative ways.

According to a first variant, it is "shielded" by a protective layer which is not intended to block oxygen but blocks corrosive substances of the Na ₂ O type by creating a perfectly impermeable barrier, either by being chemically inert to these corrosive substances or by having good affinity for them to filter out by absorption.

According to a second variant, the nitride is chemically modified to become more resistant, but without loss of performance it functions as a barrier to the effect of oxygen.

-3GB 299869 B6

This highly efficient solution has allowed a significant reduction in the amount of glass bending waste by greatly reducing the appearance of optical defects that have occurred so far. This approach is quite unexpected, since silicon nitride is commonly considered to be a completely resistant material from a mechanical point of view and as chemically rather inert. It could be expected that the optical defects found in the assembly could be due to layers that do not have such a degree of durability and are located below the silicon nitride layer, for example the functional layer or the first layer in the assembly that is in direct contact with the glass. Conversely, it has been found that corrosion propagates from the top layer of nitride.

The invention allows a compromise solution in the sense that despite this proven weakness, silicon nitride can be improved.

According to a first variant, the silicon nitride is therefore protected by a cover layer.

According to a first embodiment, the cover layer is placed on a layer of silicon nitride (preferably directly, but optionally also over one further dielectric type layer), either in the form of a metal or in the form of a metal oxide which is in the presence of oxygen in a substoichiometric form. This layer is intended to be completely oxidized during heat treatment. During the pre-treatment application, it preferably has a geometric thickness of at most 10 nm, more preferably between 1 and 5 nm. In fact, oxidation occurs, and thus the optical properties of the assembly are modified after heat treatment, which essentially results in increased light transmittance. However, these modifications are of no particular importance since the protective layer is preferably limited to very small thicknesses, these thicknesses being sufficient to fulfill their function. In any case, they are under complete control because the properties of the protective layer are chosen to completely oxidize during the heat treatment.

According to a second embodiment of this first variant, the protective layer is applied to the top side of the silicon nitride layer (directly or indirectly as in the previous embodiment) in the form of metal oxide, oxycarbide and / or metal oxinitride, especially up to a geometric thickness of at most 20 nm, more preferably between 2 and 10 nm. In this second embodiment, no modifications of the properties of the assembly have been observed after heat treatment, particularly with respect to the optical properties.

The protective layer, which may or may not undergo oxidation during heat treatment, comprises at least one metal whose oxide is capable of blocking, absorbing or filtering at high temperature corrosive substances other than oxygen, in particular of the Na ₂ O type. niobium Nb, tin Sn, tantalum Ta, titanium Ti and zirconium Zr. Niobium is particularly preferred because its oxide has a high affinity for alkali metals such as sodium.

According to a second variant of the invention, the silicon nitride layer is "doped" by introducing up to 25% by weight, more preferably between 3 and 12% by weight, of at least one metal. The metal is preferably aluminum.

The silicon nitride-based layer may advantageously form part of the thin-film assembly, and in particular may be above the functional layer having thermal properties, either directly or through at least one other thin dielectric or metal layer. In particular, the functional layer may be a filtering layer for protection against the effects of solar radiation, a selective layer, a low emissivity layer and / or an electrically conductive layer.

The assembly may comprise one or more functional layers, which may be of the same nature or may not be of the same nature, for example two or three functional layers.

The functional layer may be of the metal type, in particular based on silver, gold, aluminum, nickel, chromium, or it may be nitride or stainless steel. In this case, it is possible to form not only one functional layer, but at least two functional layers separated by at least one dielectric coating.

-4GB 299869 B6

These functional layers, their thicknesses and their optical efficiency characteristics are particularly described in the aforementioned patents. Particular mention may be made of the aforementioned patent EP 0 718 250, in which one or more silver layers are used in an assembly that is terminated with a layer of silicon nitride and is present only to impart "bendability" or " toughness". Mention may also be made in particular of European patent EP 0 847 965, which discloses an assembly having two silver layers designed to improve its bendability or toughness, and also using at least one layer of silicon nitride. The present invention makes it possible to further improve the quality of the assemblies described in the two patents.

In this case, the assemblies are schematically of the type: a silver layer positioned on one side between the "inner" dielectric coating (on the side of the carrier substrate) and through a thin metal layer, said "outer" dielectric coating containing a modified nitride layer of silicon according to the invention. In the case of an assembly consisting of two layers of silver alternating with three dielectric coatings, at least the "outer" (relative to the carrier substrate) dielectric layer is supplemented with a modified silicon nitride layer according to the invention.

The functional layer may also be of the metal nitride type, in particular TiN, CrN, NbN, or ZrN type.

This functional layer may also be of doped metal oxide such as ITO, F: SnO2, In: ZnO, F: ZnO, Al: ZnO or Sn: ZnO,

The present invention advantageously relates to thin layers deposited by vacuum technology, in particular by spraying, optionally using a magnetic field. In this case, it is a well-known technology of depositing metal or metal oxide layers or metal nitride or silicon nitride layers. In the latter case, target sites containing metal or silicon in a suitable reactive atmosphere with Ch or typu $ gases are used. The invention also relates to thin films deposited by other technologies, in particular processes involving pyrosis on a float glass strip, powder pyrosis or CVD (chemical vapor deposition), which are suitable for deposition of optionally doped metal oxide layers, deposition of metal nitride layers, as described in European patents EP 638 527 and EP 650 938, and for the deposition of silicon nitride based layers optionally containing oxygen and / or carbon as described in French patent application FR 97/014468 of 10 February 1997.

The invention also relates to thin film assemblies of which some layers, for example the first layers, can be applied by pyrolysis, and others, in particular the following layers, by means of vacuum technology in a subsequent operation.

As mentioned above, the present invention also relates to the use of a substrate coated according to the invention for the manufacture of windows which utilize the electrical properties of the functional layer (s) of the assembly as heated windows, and their use for producing windows having the above thermal which are further bendable and curable.

The invention relates to the use of these windows both in the building industry and as motor vehicle windows, wherein the glasses have a "monolithic" structure (a single solid substrate), or are laminated from two solid substrates or are asymmetrically laminated (one glass substrate combined with at least one layer of a polymer that absorbs mechanical energy and a so-called polymer layer of self-repairing type, both of which are generally polyurethane-based, as described in European patent EP 683 757). Particular mention should be made of vehicle windshields and side windows.

The invention is advantageous irrespective of the foreseen bending or bending and curing technology. In this connection, the following examples may be mentioned, but the scope thereof is not exhaustive:

-5GB 299869 B6

Technology of bending glass substrates guided through a curved profiled bed, consisting in particular of straight and curved rotating rollers as described in European patents EP 133 114, EP 263 030, EP 474 531 and EP 593 363.

Gravity bending technology, where the glass substrate, or two glass substrates one above the other, is placed horizontally on peripheral bending molds placed on support members that move through the heating furnace as described in European patents EP 317 409, EP465 308, EP 640,569 and International Patent Application Publication No. WO 97/23420, the technology being particularly adapted for the production of laminated windows.

Bending technology that uses a pressing and / or suction step against an upper rigid bending frame coupled to a lower annular bending tool, as described in European Patent Nos. EP 324 690, EP 438 342, EP 665 822, EP 459 898, EP 578 542 and EP 660 809.

The curing operation, particularly heat curing, may complete or replace these bending operations. In all cases, this requires reheating the glass to a temperature of at least 500 ° C, usually to a temperature of about 550 ° C to 620 ° C, which are temperatures that assist the corrosive action of some kinds of Na ₂ O vapors on which the present invention is based.

Description of attached pictures

The invention will be explained in more detail with the aid of the figures described below, and in the accompanying drawings:

Figure 1; a glass substrate coated with a thin film assembly comprising a silver layer; Figure 2: a glass substrate coated with a thin film assembly comprising two layers of silver; and Figure 3; a laminated window comprising the substrate of any one of Figures 1 and 2 after bending.

These figures are entirely schematic and do not respect the thickness ratios of the various materials illustrated, for this reason to better illustrate the invention. A more detailed description of these figures will be made in the examples below.

DETAILED DESCRIPTION OF THE INVENTION

The solution of the present invention will be described in more detail below with reference to specific examples, which are illustrative only and not limiting.

Example 1

This exemplary embodiment relates to the glass substrate 1 shown in section in Figure 1, namely a 2 mm thick flat substrate made of float silica-calcium-lime glass on which a stack of layers described in EP 0 718 250 has been deposited, which was better modified according to the invention, it is an assembly:

Glass ^(L) / Si3N4 ⁽² VZnO ^<3) / Ag ^(4> / Nb ⁽⁵⁾ / Si3N4 ⁽⁶⁾ ZNb ⁽⁷⁾ ··

All of these layers were sprayed.

The coating apparatus was equipped with at least one spray chamber and cathodes equipped with targets made of a suitable material, under which the substrate passes sequentially. The recommended coating conditions for each of the layers in this example are as follows:

-6GB 299869 B6

The silver layer 4 (functional layer) is deposited by means of a silver target in an argon atmosphere.

The silicon nitride-based layers 2 and 6 are deposited by reactive sputtering under a nitrogen atmosphere with a target made of 1% boron doped silicon.

Layer 3 ZnO is deposited by reactive sputtering in an argon-oxygen atmosphere containing approximately 40% oxygen by volume using a zinc target.

The 5 Nb (metallic layer) layer for protecting the silver layer is deposited by spraying in an inert argon atmosphere using a zNb target.

The layer 7 (protective layer) according to the invention, designed to protect the underlying layer of Si 3 N 4, designated 6, is deposited under the same conditions as the layer Nb 5.

The current densities and the feed rates of the substrate are adjusted in a manner known per se to obtain the desired layer thicknesses.

Table 1 below shows the nature of the layers and their thickness in nanometers in the layer assembly 20 of Example 1:

Table t

Example 1 Si3N4 (2) 20 May ZnO (2) 20 May Ag (4) 1.0 Nb (5) 1 NETWORK ₃ N '(6) 40 Nb (7) 2

Example 2

This example relates to the glass substrate 11 shown in section in FIG. 2, which is identical to the previous substrate I in FIG. 1, on which there was deposited an assembly comprising two layers of silver, the assembly being of the same type as shown in FIG. European patent EP 0 847 165 mentioned above, and better adapted according to the invention, in particular the following assembly:

glass ⁽ '' VSnO2 ^<8) / ZnO ^< ' ⁾ / Ag ^{( >)} / Nb ^{( )} / Si3N4 ^<12 ' / ZnO ⁽¹ ' ⁾ / Ag ^(14, / Nb ^<15, / Si3N4 ⁽⁶⁾ / Nb ^<17 )

The individual layers were deposited under the same conditions as in Example 1. In this case, the SnC > 2 layer was sprayed in a reactive oxygen-containing atmosphere using a tin target.

Table 2 below shows the nature of the layers and their thickness in nanometers:

-7EN 299869 B6

Table 2

Example 2 glass (! ') - SnO _{2 (} 8) 20 May ZnO (9) 17 Ag (10) 9 Nb (10) 0.7 Si3N4 (12) 55 ZnO (12) 25 Ag (14) 9 Nb (15) 0.7 Si3N4 (16) 37.5 Nb (17) 2

Each of the coated substrates of Examples 1 and 2 was then subjected to gravity bending in an annular mold mounted on a moving support unit that was moved by an overheating furnace. A second glass substrate 29, identical to substrates 1a, 1, was deposited thereon in an annular form, but this substrate was not coated. This stack of layers is located on the upper side of the substrate i and V and is therefore in contact with the underside of the second substrate (the term "in contact" does not necessarily mean continuous contact since air may be trapped at the interface of both substrates). Thus, after the bending operation, the layer stack was in the concave side of said first substrate ial. The two superposed substrates were then separated and then, in a manner known per se, bonded with 0.8 mm thick polyvinylbutyral films to form the laminated window shown in Figure 3, which can be used as a vehicle windshield.

In a conventional manner, the faces of the glass substrates 1 and 29 are numbered starting with the face that is intended to be external when placed in a vehicle. In this case, there is a concave face 2 of the multilayer assembly.

Alternatively, the laminate assembly may preferably be a face of the concave side of the assembly 3. In such a case, the bending operation is performed such that in the annular mold the substrate 1, Γ with the layers on top of the substrate 29 is free of layers.

The substrates of Examples 1 and 2 were examined before and after bending and then after painting.

The conclusions were as follows:

After bending, the light transmittance of the substrates i and V increased, which means that the final protective layer Nb "encapsulating" the underlying Si 3 N 4 layer was completely oxidized.

-8.

Compared to substrates that did not contain an Nb ending layer, the optical quality was higher, no or almost no holes appeared, and the thermal effect was also maintained.

The light transmittance of the substrate did not change.

The laminated windows obtained met all the required criteria for use as a windshield.

It should be noted that, as an alternative to the end layer Nb, it is also possible within the scope of the invention to form a thin layer of tin, zirconium or titanium (or directly deposit layers Nb ₂ O ₅ , SnO ₂ , ZrO ₃ or TiO ₂ ). In particular, Nb, Sn and Ti, in fact all have the common property of oxidizing to form compounds with sodium, thus limiting its diffusion into the underlying layers.

Claims (14)

20 1. A transparent substrate (1, Γ) for glazing of the glass substrate type, coated with a coating system comprising at least one functional layer (4, 10, 14) having sun protection, low emissivity and / or electrical conductivity, and whose the final layer (6, 16) is based on silicon nitride, carbonitride, oxinitride or oxicarbonitride, characterized in that said layer based on nitride, carbonitride, oxinitride or oxicarbonitride of silicon 25 (6, 16) is covered with a protective layer (7, 17) having a maximum thickness of 10 nm deposited in the form of a metal selected from the group comprising at least one of the following metals: Nb, Sn, Ta, Ti and Zr or deposited in the form of metal oxide; optionally with respect to a substoichiometric oxygen content selected from the group consisting of at least one of the following oxides: niobium oxide, tin oxide, tantalum oxide, titanium oxide and zirconium oxide. 2. Transparent substrate according to claim 1, characterized in that the layer based on nitride, carbonitride, oxinitride, or silicon oxycarbonitride is additionally doped by introducing into its composition at least one type A1 metal in a proportion ranging from 3 to 3. up to 25% by weight. Transparent substrate according to claim 1 or 2, characterized in that the protective layer (7, 17) is deposited in the form of a metal or in the form of a metal oxide which is substoichiometric in terms of oxygen content and oxidizes completely during the bending-type heat treatment. and / or claim. 40 The transparent substrate according to claim 3, characterized in that the protective layer (7, 17) deposited in the form of a metal or in the form of a metal oxide which is substoichiometric in terms of oxygen content, having a thickness in the range of 1 to 5 nm. Transparent substrate according to claim 1, characterized in that the protective layer (7, 17) deposited in the form of a metal oxide has a thickness ranging from 2 to 10 nm. Transparent substrate according to one of the preceding claims, characterized in that said functional layer (4, 10, 14) is of the metal type, in particular based on silver, gold, aluminum, nickel, chromium or stainless steel. Transparent substrate according to one of claims 1 to 5, characterized in that said functional layer (4, 10, 14) is of the metal nitride type, such as TiN, CrN, NbN, or Grains. -9EN 299869 B6 Transparent substrate according to one of claims 1 to 5, characterized in that said functional layer (4, 10, 14) is of the doped metal oxide type, such as ITO, F; SnO ₂ , In: ZnO, F: ZnO , AkZnO or Sn: ZnO. 5 Transparent substrate according to one of Claims 1 to 6, characterized in that it is provided with a thin film stack comprising at least one silver-based layer (4) interposed on one side with an "inner" dielectric coating (2), 3) and on the other hand an "outer" dielectric coating (6), preferably this silver-based layer (4) is located on a thin metal layer (5) located on the "inner" dielectric coating (2, 3), said outer the dielectric coating also comprises a silicon nitride-based layer (6). Transparent substrate according to one of the preceding claims, characterized in that the thin film assembly comprises at least two functional layers, in particular two or three silver-based layers (10, 14). Transparent substrate according to one of the preceding claims, characterized in that the assembly comprises one or two functional layers based on silver and a final layer based on silicon nitride. 20 May Transparent substrate according to one of the preceding claims, characterized in that it is bendable / curable. Use of a substrate according to any one of the preceding claims for the manufacture of glazings having electrical properties, such as heated glazing, and / or having thermal properties, such as protection 25 low-emission glazing that is bendable / curable. Use of the substrate according to claim 13 for the production of monolithic or laminated glazing, in particular glazing intended for use in buildings or cars as windscreens or side windows 30 glass.